<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      div {
        width: 300px;
        background-color: rgba(0, 0, 0, 0.3);
        padding: 10px;
        position: relative;
      }
      input {
        border: none;
        padding: 10px 20px;
        width: 300px;
        box-sizing: border-box;
      }
      div > img {
        position: absolute;
        top: 14px;
        right: 30px;
      }
      p {
        font-size: 12px;
        line-height: 32px;
        color: red;
        margin: 0;
      }
    </style>
  </head>
  <body>
    <div>
      <input type="text" id="username" placeholder="请输入用户名" />
      <img
        src="http://doc.canglaoshi.org/tstore_v1/images/login/yhm.png"
        alt=""
      />
      <p>用户名不能为空！</p>
    </div>
  </body>
</html>
